This invention relates generally to gas turbine engines and more particularly, to transition pieces used with gas turbine engines.
At least some known gas turbine engines include a transition piece that is coupled between a combustor assembly and a turbine nozzle assembly. To facilitate controlling operating temperatures of the transition piece within known engines, cooling air is channeled from a compressor towards the transition piece. More specifically, in at least some known gas turbine engines, the cooling air is discharged from the compressor into a plenum that extends at least partially around the transition piece of the combustor assembly. A portion of the cooling air entering the plenum is supplied into a channel defined between an impingement sleeve extending around the transition piece and the transition piece. Cooling air entering the cooling channel is discharged towards a combustor.
To enhance the effectiveness of the cooling air in the channel, at least some known transition pieces include axially-spaced turbulence-promoting ribs or turbulators, that extend outward from an outer surface of the transition piece. Known transition piece turbulators are oriented substantially perpendicularly to the flow of the cooling air in the cooling channel. These known transition pieces create turbulence by attaching a plurality of turbulators on a surface over which the air travels which creates air turbulence. When air flow comes into contact with the axially adjacent circumferential turbulator rings, the air flow slows as the air is forced over the turbulators and the pressure drop across the transition piece increases. To facilitate reducing such pressure drops, at least some known transition pieces are fabricated with a limited number of turbulators. However, as the number of turbulators is decreased, the efficiency of cooling the transition piece may also be decreased.